Question

If triangle ABC is Congruent with triangle DEF the length of side DE is:

Answer 1

The key to this problem is in the statement of congruence:
If: ABC ≅ DEF, then we can state that side AB ≅ side DE since they are in the same position within the congruence statement..

As a side note: you can also state the remaining congruence of corresponding sides and angles as well..

So your answer is: 23

Answer 2

AB is congruent to side DE.

So,

AB= 23 and DE= 23

I hope this helps!
~kaikers